NAND flash memory, as well as other types of non-volatile memories (“NVMs”), are commonly used for mass storage. For example, consumer electronics such as portable media players often include flash memory to store music, videos, and other media.
A system having an NVM may include index pages stored in the NVM that indicate the mapping statuses of logical block, addresses (“LBAs”). For example, if the mapping status of a LBA is “mapped”, this can indicate that the LBA is currently associated with data stored in the NVM. Alternatively, if the mapping status of a LBA is “unmapped”, this can indicate that data previously mapped to the LBA has been erased or the LBA has never been mapped to any data.
Because mapping statuses of LBAs are stored in the index pages, the system needs to update an index page each time a LBA is mapped or unmapped, thereby causing programming operations to be performed on the NVM. Because of the additional programming operations, the system eventually needs to perform garbage collection on the NVM in order to free up space. This in turn reduces system performance.